-LRB- CNN -RRB- -- I remember fragments of the story of SeaWorld trainer Dawn Brancheau 's killing in 2010 -- something about a ponytail , something about her slipping and falling , something about how this almost never ever happens because in these parks , the animals are happy and the trainers are safe .

But something was n't right . I remember asking someone why an orca -- a highly intelligent animal -- would attack its trainer or essentially `` bite the hand that feeds it . ''

We sometimes hear of dogs mauling other people , but in these cases we do n't seem to hear about them attacking their masters . So why would America 's lovable Shamu turn against us ? How could our entire collective childhood memories of this delightful water park be so morbidly wrong ?

I came in with these questions . I set out to understand this incident , not as an animal activist -- because I 'm not one -- but as a mother who had just taken her kids to SeaWorld , and of course as a documentary filmmaker who unfortunately ca n't let sleeping dogs lie .

SeaWorld answers questions about ` Blackfish '

I brought Manny Oteyza aboard as the film 's producer , and he soon became my right arm . I spoke to Tim Zimmermann who wrote a phenomenal article for Outside magazine about killer whales and asked him to come aboard as an associate producer . I wrote a treatment . We were then funded by investors who had never made a film before . Together we set out to tell this story of an incident at SeaWorld .

I knew immediately that I wanted SeaWorld to have a voice in the film . We e-mailed back and forth for about six months . I gave them every chance to talk , but they eventually declined . At that point , however , I had already began peeling back the onion . And my journey of shock and discovery was well underway .

I have made television documentaries for 15 years , but `` Blackfish '' is my second feature documentary and my first one to have found theatrical distribution . I ca n't say this was an easy film to make . There were nightmares , too many autopsy reports , sobbing interviewees and unhappy animals .

And I was scared . SeaWorld is a $ 2 billion a year entity , and they 'll do anything to protect their greatest asset : Shamu . But as I moved forward I knew that in telling this story in an honest and fact-driven way , I was telling the truth . It sounds clichÃ © but it 's really that simple . At some point you 're simply compelled , in spite of yourself , to tell a story that needs to be told no matter how scared you are of an entity that could squash you .

Opinion : ` Blackfish ' ignores SeaWorld 's benefits to conservation , research

Two years after I wrote the treatment in 2010 we finished `` Blackfish . '' I can say that my crew and I are all profoundly changed by the experience . I know that killer whales are not suitable for captivity . I am dedicated to spreading the word . The early deaths , the grieving , the boredom , the daily fighting and the attacks -- what we learned over two years is impossible to shake . Once you see it , you ca n't unsee it .

My hope is that we take the `` Blackfish '' momentum and use it to help evolve us out of animals for entertainment . These silly marine park tricks are of no social , educational or conservational value . We advocate , instead , for captive killer whales to be retired into sea sanctuaries where they can live out the rest of their lives in a dignified , sustainable manner .

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We ca n't throw them back into the ocean because they do n't know how to hunt , their teeth are broken from years of stress and biting on metal gates , and they 're hopped up on antibiotics and might die in the open ocean . However , in a sea sanctuary , where a large ocean cove is cordoned off with a net , we could monitor their health , even feed them if need be . It is the best alternative .

People always wonder whether I believe SeaWorld should be closed down . I always say no . They have tremendous financial resources and could play a key role in creating sea sanctuaries which could be a profit-making endeavor . I believe people would flock to a site where a killer whale is being a killer whale for the first time -- something infinitely more satisfying than seeing a killer whale dance the Macarena .

I hope you like the film . I do n't know if it will change the way you feel about animals in entertainment parks . I did n't intend for it to do so . I just wanted to tell the real story . And I trust that once audiences are armed with the truth , they will make the best decisions by themselves and their families .

The opinions expressed in this commentary are solely those of Gabriela Cowperthwaite .

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Gabriela Cowperthwaite is the director of `` Blackfish ''

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Her film explores the controversy about keeping orcas in captivity

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Cowperthwaite says she sought to answer questions about Dawn Brancheau 's death

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Watch an encore of `` Blackfish '' on CNN , Saturday , Nov. 2 at 9 p.m. ET